This invention relates to an electronic control circuit for automatically controlling the operation of a magnetic tape recording and playing unit. More specifically, this invention relates to an electronic control circuit for automatically stopping the unit tape drive motor at preselected points along the tape and in accordance with the mode in which the unit is operating.
Multi-track tape recording and playing units are commonly operable in a plurality of different modes of operation. These modes are, for example, the record mode, the record fast forward mode, the play mode, and the play fast forward mode. In at least some of these modes, it is often desirable to provide control means for automatically stopping the magnetic tape drive mechanism to stop conveyance of the tape at selected points along the tape, such as for example at the end of a particular program track. Such automatic stopping is particularly desirable when the recording and playing unit is operated in the record mode, or in one of the fast forward modes. Alternatively, it is desirable to inhibit the control means to prevent stopping of the tape drive when the unit is operated in the play mode to allow the unit to continuously switch to and play successive program tracks on the tape.
Typically, the control means for automatically stopping the tape drive mechanism of multi-track recording and playing units comprises an electromechanical relay system having various normally-open and normally-closed contacts. Such contacts are usually interconnected to the unit record/play head, and are appropriately closed and opened to effect the desired stopping of the drive mechanism. However, such electromechanical relay systems are complicated by the numerous possible modes of operation of modern tape recording and playing units, since automatic stopping of the tape drive is neither necessary nor desirable in some modes of operation. Moreover, electromechanical relay systems are inherently unreliable for long periods of use since the contacts can wear out or become pitted, and thereby require replacement. Furthermore, the conventional relays are relatively bulky and expensive, and are generally incompatible with the miniaturization requirements of modern multi-track units.
The present invention overcomes these inherent disadvantages by providing an electronic control circuit for automatically stopping the tape drive mechanism of a recording and playing unit in accordance with the mode of unit operation. Moreover, this invention provides a control circuit which is compatible with modern solid state techniques, which is relatively inexpensive, and which is inherently long-lived.